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JEE PHYSICS MCQ: WORK-ENERGY-POWER
1
Medium
1 of 1
Understanding
+4 | -1
Statement-1 : Work done is positive when force acts in the
direction of displacement.
Statement-2 : Work done by friction force cannot be positive
direction of displacement.
Statement-2 : Work done by friction force cannot be positive
View answer and explanation
Correct option: C
Statement-1 is true, Statement-2 is false.
Option C (Statement-1 is true, Statement-2 is false) is correct because work done is positive when the force acts in the direction of displacement, but work done by friction can be positive in certain situations.
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A ball throwing cannon, lifts ball and throws with Speed. If balls are raised upto . then find Input power of cannon if it lifts 8 balls per minute and its efficiency is . Mass of each ball is .
Assertion:When a particle moves in a circle with a uniform speed its acceleration is constant but the velocity changes.
Reason: Angular displacement is not an axial vector. A body of mass thrown vertically upwards attains a maximum height . As what height will its kinetic energy be of its initial value? Assertion: Centripetal force does no work.
Reason: Force and displacement are perpendicular to each other. Statement I: Both stretched and compressed springs possess potential energy.
Statement II: Work done against restoring force is stored as potential energy. A bullet of mass moving at a speed hits a ball of mass kept at rest. A small part having mass breaks from the ball and sticks to the bullet. The remaining ball is found to move at a speed in the direction of the bullet. Find the velocity of the bullet after the collision.
Reason: Angular displacement is not an axial vector. A body of mass thrown vertically upwards attains a maximum height . As what height will its kinetic energy be of its initial value? Assertion: Centripetal force does no work.
Reason: Force and displacement are perpendicular to each other. Statement I: Both stretched and compressed springs possess potential energy.
Statement II: Work done against restoring force is stored as potential energy. A bullet of mass moving at a speed hits a ball of mass kept at rest. A small part having mass breaks from the ball and sticks to the bullet. The remaining ball is found to move at a speed in the direction of the bullet. Find the velocity of the bullet after the collision.